Means for preventing current leakage in electric cables.



S. D. SPRONG & W. E. MCCOY.

MEANS FOR PREVENTING CURRENT LEAKAGE IN ELECTRIC CABLES.

APPLICATION HLED FEB.12.1915.

1,165,140. Patented 1160.21, 1915.

ITED STATES PATENT OFFICE SEVERN D. SPRONG AND WALTER 152. LLYZGQQY, YORK, 34'. Y.

MEANS FGR IPREVENTING CURRENT LEAKAGE ELECTRIC CABLES.

Application filed February 12, 3.9

if?) Q33 20 am may, concern Bo i 4 AND that we, Slaw a and i' ALTER MCCOY citizens of the United biz mes, residing at New York, in county New York and State of New York, e ini ented a certain new and usefiii Iii'ipiwrvemmt 'ip Means for Preventing Current Leakage in Electric Cables, of; which the following is a specification.

For convenience of manufacture and Tm (fling, electric cables are mzuie in oro lengths joined together usuz'siiy after being placed in position Much difiiouity has been experienced in prev 'igg leaka e at the joints between the severe line conductors Whici Foi'm. the onbie and which are usiieiiy embe in an lnsuiating compound i i} fills the protective incioeing meta sheave. The or imry way of making these joints is, after 1 1e metallic conductors are expose and united at their extremitiesi, ti) "vs rap conductors with layers of insuiatizig mpe with intervening coatings of varnish oi the like, until desired thickness of envelop oiz mine2i or sometimes by cove the metallic joint, with a tube of insuiating mm teriei, In using 1310 first method it; often happens but owing to the location of the joint it is impossibie to get such aocess to the as that the insulating trapecan be evenly wound thereon or die varnish can be agpiiecl so as to insure its perooia space between ii Hence the 1&3

contains 11' the insuiati In the second tube is we insulation of it the oondoctore for in *uietin remo e Lhe a length in ex ess of the length of the t me, since it necessary in oi iei' to apply the tube 0 i ant to thread one oI the conof Wrapping and varnish layers between the Specifioation 0i Leccers Patent.

Patenteifi Dec, 21, 191150 tube and the conductor, ii; is zieoessarv make the tube of large diimeter. am in turn correspondingly inczeasses the eter the lead sieeve which final! he 'z iei ieaiiy seals) the joint, v

The arinoipie of our invention if 5 construct the joint covering as Him; a dieieetrio strenyth of the insuiziiion between the severe? conductors between each so to? zmci the oilier sheath-hence growl? w vi1i 1e greater than bet i-Xililfifii; 111g This We effect means of inciosing zi'ziiteriai of high dieleo i i are eppiied to the i W conduct iai'eraii or, in other woicie,

f threading the conductors through them anoi which are embedded in i M Eating eompoimd Whi h fills the seem} i The reiative arrangement ofthe ti" such that e creeping current; must fir thyough the insulin" g fiiiing Wit tube to a gap in the tube Willi, i313 through the insuiating filling ontsisie .L

to his & til-cent tube, and then ihioug'h the in that tuoe before it can from conductor to another.

In the accompanying drawings Figure 1 av longitudinal section of our cabie joint on the line "i 1 of Fig. Fig. 2 is an e1evation of the comple joint :1 portion. being broken away. Fig. 8 is a cross seciion 1e 3 3 of Fig L Fig 4 Silfliseciion of a IflOCiifiiiHiiOEl of our :mmibers anci letters of iefezence psi-Tia Jie here eizown commie-s ibreo is Uonductoi's A B, C, eaoh having the ills-ting cover D, and 3,11 ineioseii n E, usueily of lead. The space heath not occup ed by said canfiiied with an @miaifi ir*io('ii.iee-ii in a piasiie e1 owed to harden We plain the opei'ation. of forming and GOV duciiorsi it being the same for ali. sheath out away and then. the insulating filling compound, as shown. at 3 and 4-, so as to expose asufficient length of the cover g a I), when in turn 13 cut away, as shown at w, 0: so as to expose the naked wires of the iii reference to one of said. son 7 conductor l3, l3. l'ipon the sheath E of one part of the cable is slid a tube G of fiber or other insulating material which is pushed back on said sheath, as shown in dotted lines. Fig. 1, so as to be well away from the joint. l'pon the tube (l is placed a section of lead sheathing H, and this is also slid back from the joint in the same way as is tube (i. The ends of conductor 13, B being cut olt squari and approximated face to face. are inserted in a short copper sleeve I, having openings through which molten tin or solder is run. Said tin binds the said approximated ends together and fills the annular space between said sleeve and said wires and also the openings in said sleeve. We then place upon the conductor a mutilated tube J of lcnticular or elliptical cross section and made of fiber or other material of high dielectric strength. Said tube extends over the sleeve l and exposed ends of conductor l3. l3 and may. if desired, reach to the shoulders formed by cutting away the insulating filling F at 3, -t. In the wall of the tube J is a gap K, through which the conductor passes when the tube placed thereon. This gap is located at one end of the major axis of the elliptical figure formed by a cross section of the tube. The gap may be enlarged to permit the passage of the conductor by springing its edges apart. The. conductor is. therefore, not threaded through the tube from end to end, but the tube is placed bodily upon the conductor after the joint between the meeting ends thereof is formed.

The ends of the other conductors of the cable are joined in the manner already described, and tubes ll. M, similar to tube J, are applied thereto. The tubes J, L, M are to be so placed relatively to one another that their gaps, similar to K, are all turned in the same direction, as shown in Fig. 3. After the three tubes J, L, M have been put in place, we slide the tube G longiudinally until its ends lap over the cut off end portions of the insulating filling F, as shown in Fig. l. lVe then slide the sheath section H in like manner, so as to cover the tube G, and so that its extremities will lap over the ends of the lead sheath E on the cable. We then bend inwardly the extremities of the tube section H until they meet sheath E, and between said extremities and said sheath we form with solder a. wiped joint. as shown at N, Fig. 2. Openings are made in tube H by suitably cutting the wall thereof and bending back the same, as shown at 0. Fig. 1. 'lhrough these openings is poured viscid or plastic insulating compound, which then fills all the open spaces within said sheath and there hardens.

In the modification shown in Fig. 4. curved plates P, Q, R, also of material of high dielectric strength, are placed between the conductors A, B, C. The widths of these plates are such that their outer edges meet the inner periphery of tube G, so that they form' partitions dividing the space within said tube into three compartments, each containing one conductor and its surrounding mutilated tube.

By the before described construction, we reduce any possible leakage of current between the conductors A, B, C to a minimum. The dielectric strength of tubes J, L, M is greater than that of theinsulating filling F. Hence the current on one conductor, as C. Fig. .3, cannot find its way either through said filling directly to either of the other conductors, but must proceed over a path. represented by the curved arrow It in Fig. 3, that is, from conductor C, through the gap in tube M, then through the insulating filling to the gap in tube L, and so to conductor A. The length of this path is obyiously longer than the thickness of the insulating filling measured in a straight line from conductor C to conductor A. Hence the effect of the added tubes J, L, M is substantially largely to augment the resistance offered to the passage of the current from one conductor to the other without requiring any actual increase in distance between these conductors or enlargement of the cable di ameter. So also the intervention of the tubes J, L, M between the cables A. B, C and the outer sheath along the line largely increases the resistance in the path of current proceeding froni the conductors to said sheath and ground.

ltn the form shown in Fig. i, the path of the leakage current is still further obstructed by the partitions P, Q R.

l/Ve claim:

1. An electric cable, comprising an inclosing tube, a jointedline conductor therein, a filling of insulating material in said inclosing tube, and a tube of insulating material embedded in said filling and inelosing said joint; the said last-nzuned tube being substantially elliptical in cross section and of material of greater dielectric strength than said filling and having a longitudinal gap in its wall located at one end of the major axis of said cross sectional ellipse.

2. An electric cable. comprising an inclosing tube, a plurality of jointed line conductors therein. a filling of insulating material in said inclosing tube, and tubes of insulating material embedded in said filling and respectively inclosing said conductors: each of said last-named tubes being substantially elliptical in cross section and of material of greater dielectric strength than said filling and having a longitudinal gap in its wall located at one end of the major axis of said cross sectional ellipse, and the said major axis lying eachlat an angle to a radius struck from the center of the circular/cross section of said inclosing tube, and the gap in each inner tube being approximated to the Wall of the next adjacent inner tube.

3. An electric cable, comprising an inclosing tube, a plurality of longitudinal partitions of insulating material therein forming compartments, a jointed conductor disposed in each compartment, a filling of insulating material in said compartments, and in each compartment a tube of insulating material embedded in said insulating filling and inclosing the conductor therein: each of said lastnamed tubes and said partitions being of material of greater dielectric strength than said filling.

4. An electric cable, comprising an inclosing tube, longitudinal partitions of insulating material in said tube dividing the same into compartments, a plurality of jointed conductors respectively disposed in said compartments, a filling of insulating material in said compartments, and tubes of insulating material embedded in said filling and respectively inclosing said conductors: each of said last-named tubes and said partitions being of material of greater dielectric strength than said filling and each of said inner tubes being substantially elliptical in cross section and having a longitudinal gap in its Wall located at one end of the major axis of said cross sectional ellipse, and the said major axes lying each at an angle to a radius struck from the center of the circular cross section of said inclosing tube, and the gap in each inner tube being approximated to the wall or" the next adjacent inner tube.

In testimony whereof We have alfixed our signatures in presence of two Witnesses.

SEVERN D. SPRONG. WVALTER E. MCCOY. Witnesses:

GERTRUDE T. PORTER, MAY T. MoGARnY. 

